In the 3GPP (3rd Generation Partnership Project), which is a standardization project, Evolved Universal Terrestrial Radio Access (hereinafter also referred to as “EUTRA”) has been studied, in which the OFDM (Orthogonal Frequency-Division Multiplexing) communication scheme and flexible scheduling on the basis of a predetermined combination of a frequency and time called a resource block are adopted to achieve high-speed communications. Furthermore, the study of Advanced EUTRA (also referred to as “LTE-Advanced”), which is an advanced version of EUTRA, is underway.
In Advanced EUTRA, a technique called carrier aggregation that enables higher-speed data transmission while maintaining compatibility with EUTRA has been proposed. Carrier aggregation is a technique in which data of a transmitter device transmitted using a plurality of different frequency bands (also referred to as “carrier frequencies” or “component carriers”) is received by a receiver device handling the different frequency bands respectively to thereby increase a data rate. In the description below, a receiver device and a transmitter device in downlink transmission are referred to as a “mobile station device” and a “base station device” respectively, and a receiver device and a transmitter device in uplink transmission are referred to as a “base station device” and a “mobile station device” respectively; however, the scope of application of the present invention is not limited to these devices.
Component carriers used in carrier aggregation in Advanced EUTRA are classified into a Primary Component Carrier (PCC) and a Secondary Component Carrier (SCC). A cell to which a mobile station device is connected using a PCC in downlink is called a “Primary Cell (PCell)” while a cell to which a mobile station device is connected using an SCC in downlink is called a “Secondary Cell (SCell)”. An uplink component carrier is always included in the primary cell but is not included in some secondary cells.
A mobile station device based on EUTRA performs processing for transmission timing adjustment for uplink (synchronization of uplink) called a “random access procedure” when initial connection to a base station device is attempted, when handover is performed, or when uplink data transmission or downlink data reception needs to be performed in the state where uplink is out of synchronization. It is specified in the current Advanced EUTRA that the random access procedure is performed only in the primary cell (see NPL 1).
The third generation base station device specified by 3GPP is called a “NodeB” and the base station device in EUTRA and Advanced EUTRA is called an “eNodeB”. A base station device controls a cell, which is an area in which a mobile station device can perform communication. The cell is also called a “femto cell”, a “pico cell”, or a “nano cell” in accordance with the size of the area in which a mobile station device can perform communication. In the case where a mobile station device can communicate with a certain base station device, the cell of the base station device is called a serving cell of the mobile station device, while a cell of another base station device or of a different frequency is called a neighboring cell.